Girder type switch track

ABSTRACT

A switch track for switching a girder type track between a plurality of stationary tracks comprises a movable track girder including a drive girder and at least one driven girder. One end of the driven girder is rotatably supported at a predetermined point located on the ground, and the other end of the driven girder is connected to the drive girder. The drive girder is driven by a drive arrangement to pivot at one side thereof adjacent to the driven girder, around an imaginary center common to both of its ends, in order to enable it is move between connecting points of respective main tracks. The driven girder is moved only by driving the drive girder, such that the movable track girder is switched between connecting paths to the respective main tracks.

DESCRIPTION

1. Field of the Invention

The present invention relates to a girder type switch track for use in abranching point of a girder type track for guiding a car such as amagnetic levitating type linear motor car or a monorail car.

2. Background of the Invention

As a girder type track for guiding a vehicle, one for supporting andguiding the monorail car is well known.

A known switch track for use in a switch portion of such girder typetrack comprises a girder portion disposed between a stationary maintrack and a plurality of stationary other tracks. The girder portion isturnable at its end adjacent to the main track so that the other end canbe connected to any of the other tracks In such girder type switchtrack, in order to obtain a sufficient deflection of the track withusing a single such girder portion, the latter should be long enough tosmoothen a turning of a car guided thereby. Further, when such girderportion is turned around the one end thereof, an angle of the girderportion with respect to the main track becomes large, so that the carcan not be guided smoothly In order to solve this problem, it has beenproposed to constitute a switch track with a plurality of girderportions mutually turnably connected to each other to form anarticulated curve so that the car is guided smoothly along the curve.

FIG. 5 shows an example of a conventional articulated switch track 53which is used to connect a stationary main track 51 of a girder typetrack to either of two other main tracks 52a and 52b thereof. The switchtrack 53 includes a plurality (four in the illustrated example) ofgirder portions 53a, 53b, 53c and 53d. The first girder portion 53a isturnably connected at one end thereof to an end of the main track 51 bymeans of a pin 54. The second to fourth girder portions 53b-53d aremutually turnably connected to form a series connection. Each of thegirder portions 53a to 53d is driven by respective drive means. Thedrive means may be a crank mechanism having a swingable crank arm. Forexample, a crank arm 50 of a crank mechanism 55 is engaged with alongitudinal groove formed in the first girder portion 53a such that thelatter is switched between a position shown by a solid line and aposition shown by a chain line with rotation of the crank arm 56.Similarly, the second girder portion 53b is driven by a crank arm 58 ofa crank means 57, the third girder portion 53c is driven by a crank arm60 of a crank means 50 and the fourth girder portion 53d is driven by acrank arm 62 of a crank means 61. The respective crank means 55, 57, 59and 61 may be driven in symchronism with each other by a singleconnecting rod 64 which is in turn driven by an electric motor 63. Thefirst girder portion 53a is turned around the pin 54 by a predeterminedangle with respect to the main track 51, the second girder portion 53bis turned by a predetermined angle with respect to the first girderportion 53a. Similarly, the third and fourth girder portions 53c and 53dare turned, respectively. Thus, the main track 51 is connectedswitchingly to either the other main track 52a or 52b.

In this conventional switch track, there are provided gaps between thefourth girder portion 53d and the other main tracks 52a, 52b in view ofthermal expansion of track. Further, in order to avoid collision of thefourth girder portion 53d with any of the other main girder tracks whenthe switch track is turned, the gaps provided in between the fourthtrack portion 53d and the other main tracks 52a and 52b must be largeenough, which may cause a smooth guiding of the car to be difficult.Further, due to the necessity of moving the girder portions by means ofthe respective drive means, an overall facility therefor becomes largeand expensive.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to solve theseproblems inherent to the conventional art by providing a girder typeswitch track having a simple structure and being capable of smoothingthe guiding of a car to any of other main tracks.

Another object of the present invention is to provide a simple andinexpensive switch/guide apparatus for making a gently curved track in abranching point.

A further object of the present invention is to minimize gaps necessaryin between stationary tracks and a switch track as well as in between aplurality of movable track portions.

A still further object of the present invention is to simplify theprocessing of loads, including a braking force and a driving force, onthe car in a running direction thereof.

Another object of the present invention is to prevent an excessive loadin an unusual case when switching/guiding is done.

In order to achieve these objects, a switch track for switching a girdertype track between a plurality of stationary tracks, according to thepresent invention, comprises a movable track girder including a drivegirder and at least one driven girder having one end rotatably supportedat a predetermined point located on ground and the other end connectedto the drive girder or driven girder through a connecting means, such asa link. The connecting means is capable of transmitting a movement ofthe drive girder or driven girder in a direction orthogonal to alongitudinal axis of the movable track girder to the driven girder. Thedrive girder is driven by a drive means to turn at one side thereofadjacent to the driven girder around an imaginary center to therebyswitch between connecting points to the respective main tracks. Thus, bydriving only the drive girder, the driven girder or girders follow amovement of the drive girder to complete the intended switching of thegirder track.

In the present invention, the drive girder of the girder type switchtrack switches the main track between the other main tracks because itseems to be turned on the imaginary center by means of the drive means.To the end portion of the drive girder on the side of the imaginarycenter, the driven girder is connected through the connecting means suchas a link. A movement of the drive girder in the direction orthogonal tothe axis thereof is transmitted to the driven girder to turn the latteraround the predetermined point set on ground. This movement of thedriven girder is further transmitted by a link to a next driven girder,if any, to rotate the latter around its own rotation center. The samemovement may be achieved for each of subsequest driven girders, ifnecessary. Thus, when the drive girder is driven, the series connecteddriven girders are driven thereby to provide an articulated, smooth pathfrom the main track to either of the other main tracks. It is, ofcourse, possible to connect the main track to another main trackstraightly by the switch track girder with its drive girder, if thelatter track is on an extension of the main track.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a girder type switch track according to anembodiment of the present invention;

FIG. 2 is a plan view of a drive means for driving a drive girder;

FIG. 3 is a front view of a ball-screw device;

FIGS. 4a to 4d show sequential calculation of fulcrums, an imaginarycenter and standard points therefor, and FIG. 4e shows all of thefulcrums, the imaginary center and the standard points thus calculated;and

FIG. 5 shows an example of a conventional girder type switch track.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is described in detail with reference to thedrawings.

In FIG. 1, a girder type switch track 3 is provided between a main track1 of a girder type track and a plurality of other main tracks thereof.In the illustrated case, the second main track 2a and the third maintrack 2b are provided. By turning the girder type switch track 3, thefirst main track 1 is selectively connected to either the second maintrack 2a or the third main track 2b. By connecting the first main track1 to the second main track 2a, the first path is formed, while thesecond path is formed by connecting the first main track 1 to the thirdmain track 2b.

The girder type switch track S includes a movable track girder which iscomposed of a drive girder 4 and at least one driven girder. In theillustrated case, however, the first and second driven girders 5a and 5bare provided. Such a movable track girder having the drive girder 4 andthe driven girders 5a and 5b is arranged at the position where the firstand second paths are formed in order to be gently curved paths, but ifcircumstances require, either of them forms a straight path. In FIG. 1,at the first path, the drive girder 4 and the driven girders 5a and 5bform a curved path and, at the second path, they form a straight path.The respective girders 4, 5a and 5b may be provided with wheels to maketheir movement smooth.

The driven girders 5a and 5b are turnable around fulcrums fixedly setbetween the first path shown by continuous lines and the second pathshown by chain double-dashed lines, respectively. The first drivengirder 5a adjacent to the first main track 1 is turnably supported byfulcrum A set on the first main track 1. The fulcrum A is turnablyconnected to the first main track 1 (not shown in detail and aconventional mechanism is adopted therefor.

The second driven girder 5b is rotatably supported by fulcrum E set onthe ground. The fulcrum E may be constituted similarly to the fulcrum A.

The drive girder 4 is turned like being swung on an imaginary center Hset in between its positions in the first and second paths.

The drive girder and the driven girders are moved along a guide memberprovided on the ground. Such a guide member for the drive girder may beconstituted with a plurality of rails 8 and wheels (not shown) providedon the drive girder 4 and rollingly guided on the rails 8. The guidemember for the driven girders may be constituted similarly.

In order to support a longitudinal load to the drive girder, that is,the driving or braking force of a vehicle moving on the girder, theabove-mentioned wheels and guide member can be used. Alternatively, arotatable rod which may exist between the imaginary center H and the endportion of the drive girder near the second driven girder 5b can beused.

The drive device 9 may be constituted with crank arms 11a and 11brespectively engaged with longitudinal grooves 10a and 10b formed inboth end portions of the drive girder 4, sprocket wheels 12a and 12bfixed respectively to the crank arms 11a and 11b as shown in FIG. 2, achain 13 stretched on the sprocket wheels 12a and 12b and a ball-screwdevice 14 for reciprocating the chain 13. As shown in FIG. 3, theball-screw device 14 includes a drive portion 15, a screw shaft 18connected to the drive portion 15 through a universal joint 16 and aconnecting rod 17, a ball-nut 19 screwed into the screw shaft 18 and acasing 20 for reciprocably supporting the ball-nut 19. A plurality ofsuch devices 14 may be provided for emergency purpose. The chain 13 isfixed to the ball-nut 19 through a connecting rod 21. The ball-nut 19 ismoved by rotating the screw shaft 18 by the drive portion 15. Therefore,the chain 13 is moved and the crank arms 11a and 11b are rotated insynchronism therewith. With the rotation of the crank arms 11a and 11b,the drive girder 4 is moved along the rails 8, resulting in asubstantial rotation around the imaginary center H. The drive device 9may be any of other mechanisms such as a hydraulic cylinder mechanism,link mechanism, etc. Further, application of moving force to the drivegirder 4 is not limited to two points as shown. Such force may beapplied thereto at a single center point thereof.

An end of the drive girder 4 is connected to an end of the second drivengirder 5b which is located on the opposite side to the fulcrum E througha connecting member 22. The other end of the second driven girder 5b,that is, the fulcrum E-side end is connected to an end of the firstdriven girder 5a through another connecting member 22. This end issituated on the opposite side to the fulcrum A. The connecting members22 serve to transmit movements in directions trasverse to the axes ofthe drive girder 4 and the second driven girder 5b respectively to thesecond and first driven girders 5b and 5a while buffering axialmovements by absorbing them. For example, the simplest connecting membermay be a link lever 23. The link lever 23 is connected at each end tothe drive girder 4 or the second driven girder 5b and another link lever23 is connected at each end to the second driven girder 5b or the firstdriven girder 5a. In order to minimize relative deviation of axis-linesof the movable girders adjacent each other, it is preferable to arrangethe link levers 23 such that they extend in moving directions of themovable girders 4, 5a and 5b, respectively.

The rotation center, that is, the imaginary center H and the fulcrums Aand E points or fulcrums of the respective movable girders 4, 5a and 5bare set such that a gently curved path is formed by the girders 4, 5aand 5b with gaps therebetween as small as possible. In order tofacilitate the understanding of setting of them, as seen in FIGS. 4a to4e the movable girders 4, 5a and 5b are depicted by single center lines,respectively, length of the drive girder 4 by l₁, that of the drivengirder 5a, 5b by l₂, and rotation angles of the drive girder 4, thefirst driven girder 5a and the second driven girder 5b by θ₁, θ₂ and θ₃,respectively. Although, in the illustrated case, the driven girders 5aand 5b have the same length, these can be made different. It istheoretically preferable that the fulcrum A of the first driven girder 5a adjacent to the first main track 1 is set in one edge portion of thefirst driven girder 5a. In such case, the other end B of the firstdriven girder 5a moves to a point B' by rotation of the girder 5a aroundthe fulcrum A. Although it is theoretically preferable that one end ofthe second driven girder 5b moves along the same path as that of the endB of the first driven girder 5a in view of minimizing the gaptherebetween, it is impossible to make their movements identical sincethe rotation centers thereof are different from each other. Accordingly,in the second arrangement, one end of the second driven girder 5b shouldbe positioned at the points B and B' which are positions of the end ofthe first driven girder 5a when switched between the first and secondpaths. In order to realize this, the position of the fulcrum E of thesecond driven girder 5b is set on a line passing through a center pointF between the points B and B' and the point A which is the fulcrum ofthe first driven girder 5a.

The rotation centers necessary to make the curve formed by the girdersgentle is calculated with conditions l₁ =19.7 m, l₂ =4.2 m, θ₁ =7.2°, θ₂=2.4° and θ₃ =4.8°.

First, the position of the fulcrum E which is the rotation center of thesecond driven girder 5b is calculated. In FIG. 4b, depicting distancebetween B and F as a, that between E and F as b, that between A and F asc and that between A and E as d, the followings are obtained:

a=4.2 sin 1.2°=0.0879582

b=a/tan 2.4°=2.0986191

c=a/tan 1.2°=4.1990806

d=c-b=2.1004615

Depicting a cross point between a linear line AB and a perpendicularfrom the point E to the line AB by G, length of a linear line EG by eand a distance between A and G by f, the followings are obtained:

e=d sin 1.2°=0.0439887≈0.044 m

f=d cos 1.2°=2.1000008≈2.100 m

From the values of f and e, the position of the fulcrum E of the seconddriven girder 5b is set.

Next, a rotation center H of the end portion of the drive girder 4 whichis adjacent to the second driven girder 5b, that is, the end portion onthe side of C and C', is obtained such that its end coincides at thepoints C and C' with the second driven girder 5b rotating around thefulcrum E.

In FIGS. 4a and 4c, a line connecting a center point J between thepoints C and C' to the point E is a bisector passing through a center ofan arc CC' having a center point at the point E. Therefore, the rotationcenter H of the end portion of the drive girder 4 on the CC' side existson the bisector. Further, since a rotation angle of this end portion ofthe drive girder 4 from the point C around the point H is 7.2°, theposition of the point H is determined from the bisector angle 3.6°.

In FIG. 4c, assuming, <HCE=β and <ECA=γ, ##EQU1##

Depicting a cross point of the perpendicular from the point H to thestraight line AC and the line AC by K, ##EQU2##

The rotation center H of the end portion of the drive girder 4 adjacentto the second driven girder 5b can be set from k and m on the basis ofthe point C. In the described example, the point H is eccentric from thepoint B by k. As a matter of course, a rotation center of the endportion of the drive girder 4 on the DD' side is also H, and this is theimaginary center of the drive girder 4.

Just for reference, the point C is rotatively moved to the point C, byfulcruming the imaginary center H by 7.2°. A line passing through thispoint C' with an angle of 7.2° with respect to the straight line ADrepresents a position of the drive girder 4 after moved. Depicting across point of an extension of this line and the line AD by Ho (this isthe standard point with respect to installment), the end portion C ofthe drive girder 4 on the second drive girder side, that is, the point Kis moved Ko after rotated, as shown in FIG. 4d.

KHo=lo=HoKo shown in FIG. 4d is calculated. Since <KHHo=<HoHKo=3.6°,##EQU3##

Therefore, the positions of the imaginary center, the fulcrums and thestandard point of the respective girders 4, 5a and 5b become as shown inFIG. 4e.

When the drive girder 4 is guided by the guide members 8 such that thegirder 4 rotates around the imaginary center H, the driven girders 5aand 5b are rotated automatically around their fulcrums A and E by theconnecting members, providing a gently curved path or straight path,together with the drive girder.

Enlarging or reducing the rotation angles of the girders gradually inorder, it is possible to form smooth and gently curved track.

What is claimed is:
 1. A switch track for switching a girder type trackbetween a plurality of station tracks comprising:a movable track girderincluding a drive girder and at least one driven girder, one end of saiddriven girder being rotatably supported at a predetermined fulcrum pointlocated on ground, the other end of said driven girder being connectedto said one end of said drive girder through a connecting means, saidconnecting means being mounted to transmit movement of said drive girderin a direction orthogonal to a longitudinal axis of said movable trackgirder to said driven girder, and drive means connected to pivot saiddrive girder to turn at one side thereof adjacent to said driven girderaround an imaginary center to thereby move said drive girder betweenconnecting points at which said movable track is aligned with therespective station tracks, both ends of said drive girder being pivotedonly about said imaginary center, said driven girder being mounted to bedriven only by said drive girder, to thereby switch said movable trackgirder between connecting paths to said respective station tracks. 2.The switch track claimed in claim 1, wherein facing ends of said drivengirder and drive girder, which are rotated around said fulcrum point andsaid imaginary center respectively, are mounted so that said facing endstransitorily separate and take substantially the same positions withrespect to one another at each of said connecting points.
 3. The switchtrack claimed in claim 1 or 2, comprising means for reciprocating saiddrive girder by said drive means around said imaginary center and aguide member for guiding said drive girder during said reciprocation. 4.The switch track claimed in claim 1 or 2, wherein said fulcrum point andsaid imaginary center of said girders are eccentric with respect on oneanother.
 5. The switch track claimed in claim 1 or 2, wherein said drivemeans comprises a chain extending between a pair of sprocket wheels,separate cranks having different lengths coupled to said sprocketwheels, said cranks being connected to move different parts of saiddrive girder, and a ball-screw connected to drive said chain.
 6. Theswitch track claimed in claim 1 or 2, wherein said connecting meanscomprises means for absorbing distortion at both ends of said drivegirder due to positional difference of said fulcrum point and saidimaginary center of the girders adjacent to each other.
 7. The switchtrack of claim 1 wherein said fulcrum point is a point that is differentfrom said imaginary center and wherein said connecting means isconnected to transmit movement to said driven girder only in a directionorthogonal to said longitudinal axis.
 8. A switch track for switching agirder type track between a plurality of station tracks comprising:amovable track girder including a drive girder and first and seconddriven girders, one end of each of said driven girders being rotatablysupported at a separate predetermined fixed fulcrum point, the other endof said first driven girder being coupled to said second driven girderby a first connecting means and the other end of said second drivengirder being connected to said drive girder by a second connectingmeans, said first and second connecting means being mounted to transmitmovement of said second driven girder and said drive girder respectivelyin a direction orthogonal to a longitudinal axis of said movable trackgirder to said first and second driven girders, respectively, and drivemeans connected to pivot said drive girder to turn at one side thereofadjacent to said second driven girder around an imaginary center tothereby move between connecting points at which said movable trackgirder is aligned with the respective station tracks, both end of saiddrive girder being pivoted only about said imaginary center, said firstand second driven girders being mounted to be driven only by movement ofsaid drive girder, to thereby switch said movable track girder betweenconnecting paths to said respective station tracks.
 9. The switch trackof claim 8 wherein said separate fixed points are different from saidimaginary center and wherein said second connecting means is connectedto drive said second driven girder only in said orthogonal direction.